49ers' Brandon Aiyuk tears ACL, MCL; Deebo Samuel in hospital

SANTA CLARA, Calif. -- Less than 24 hours after wide receiver Brandon Aiyuk injured his right knee against the Kansas City Chiefs, the San Francisco 49ers got the bad news they were expecting.

Aiyuk tore the anterior cruciate and medial collateral ligaments in his right knee, which will require surgery and end his 2024 season after just seven games, coach Kyle Shanahan announced Monday.

What's more, the illness that limited wideout  Deebo Samuel to four snaps against the Chiefs is technically a form of pneumonia, according to Shanahan. Samuel has some fluid buildup in his lungs and remains in a local hospital after checking in Sunday night.

"I think it started acting up in the middle of the night Saturday night or early Sunday morning and then it just kind of evolved as the day went," Shanahan said of Samuel. "Once we found out he had the fluid in his lungs and stuff after the game, then I believe they sent him over there."

Shanahan said there's no timeline yet for when Samuel could return, though that should clarify over the next few days.

Aiyuk, meanwhile, is not expected back at all this season. Further tests confirmed Monday what Shanahan was expecting Sunday night. After a 28-18 home loss to the Chiefs, Shanahan said all signs pointed toward a torn ACL but a closer look was still needed and that the Niners were "praying" they were wrong. They weren't.

Aiyuk's injury happened with 48 seconds left in the second quarter. Quarterback Brock Purdy squeezed a pass to Aiyuk between Kansas City defensive backs Chamarri Conner and Trent McDuffie for a gain of 15 yards. As Conner and McDuffie converged on Aiyuk, his knee appeared to hyperextend.

Niners medical personnel immediately ran on the field to tend to Aiyuk, who stayed down for a couple of minutes before slowly limping to the sideline and the blue medical tent. He was soon taken to the locker room on a cart. 

Aiyuk had two catches for 23 yards at the time of the injury, which came amid a relatively slow start to the campaign. With his season over, Aiyuk will not be able to reach 1,000 receiving yards for a third straight year. He had 75 receptions for 1,342 yards and seven touchdowns last season en route to a second-team All-Pro nod.

"I talked with him last night, just calling him at his house," Shanahan said. "He was hurting, just bummed out, exactly how you'd expect. But he's a strong dude and spiritual guy and believes everything happens for a reason, so he'll be all right. But definitely a little down last night, and I was just telling him how bad I felt for him and just let him know we're all here for him through this."

The Niners signed Aiyuk to a four-year, $120 million extension in August after a lengthy contract dispute. He finishes this season with 25 catches for 374 yards and no scores.

Aiyuk's setback is the latest in an increasingly long list of injuries to key 49ers. Running back Christian McCaffrey (Achilles tendinitis), linebacker Dre Greenlaw (torn Achilles), defensive tackle Javon Hargrave (torn triceps) and safety Talanoa Hufanga (torn ligaments in his wrist) are among the others to miss a significant amount of time.

"It sucks," center Jake Brendel said Sunday of Aiyuk. "Any injury like that to one of your weapons on offense or defense, it just sucks. I feel like as a roster, we just have to respond. Whoever's next on the roster needs to step up and make sure that there isn't a setback in productivity on offense."

With Aiyuk lost for the season, the 49ers are hoping to get Samuel and fellow wide receiver  Jauan Jennings back for Sunday night's matchup with the visiting  Dallas Cowboys. Jennings did not play against Kansas City because of a hip injury suffered in an Oct. 10 win at the Seattle Seahawks.

If they don't get either or both of Samuel and Jennings for the Dallas game, the Niners would again have to turn to a wideout group that includes rookies Ricky Pearsall and Jacob Cowing, second-year player  Ronnie Bell and veteran Chris Conley, who is also day-to-day with an ankle injury.

"With Jauan and Deebo, not sure if we'll get them back this week or not," Shanahan said. "So, it was a good start for those guys, and they should have a lot more coming."

Tight end George Kittle, who picked up most of the pass-catching slack against the Chiefs with six receptions for 92 yards, is also day-to-day with a foot sprain.

Elsewhere on the injury front, Shanahan said the Niners do not expect to get back McCaffrey, Greenlaw or kicker Jake Moody this week, either.

"Christian's still progressing through his rehab," Shanahan said. "He hasn't had any setbacks, so it's been all good news so far. I'd be surprised to get him back this week, but hopefully the bye week will go well and have a much better chance there right after the bye week."

Shanahan indicated Moody also could return after the Week 9 bye but that Greenlaw will probably be a bit longer.